Barrier film and method for preparing the same

ABSTRACT

Provided are a barrier film and a method for preparing the same. Particularly, the barrier film is applied to an organic or inorganic phosphor, a display, or a photovoltaic device to effective block chemical materials such as water or oxygen, protect an electronic device therein, and maintain excellent optical characteristics.

This application is a National Stage Application of International Application No. PCT/KR2015/000530, filed on Jan. 19, 2015, which claims the benefit of Korean Patent Application No. 10-2014-0006133, filed on Jan. 17, 2014 and Korean Patent Application No. 10-2014-0114251, filed on Aug. 29, 2014, all of which are hereby incorporated by reference in their entirety for all purposes as if fully set forth herein.

BACKGROUND

1. Field of the Invention

The present invention relates to a barrier film and a method for preparing the same.

2. Discussion of Related Art

When electric devices and metal interconnections included in organic or inorganic phosphors, displays, photovoltaic devices, etc. are in contact with external chemical materials such as oxygen or water, they are modified or oxidized, and thus cannot be properly functioning. Accordingly, it is necessary to protect the electric devices from the chemical materials. To this end, a technique of protecting internal electric devices vulnerable to chemical materials using a glass plate as a substrate or a cover plate has been proposed. The glass plate has satisfactory characteristics including light transmittance, a coefficient of thermal expansion, and chemical resistance. However, since glass is heavy, hard, and easily breakable, it should be carefully handled.

Accordingly, there is an active attempt to replace the glass plate used as a substrate for an electric device with a plastic film or sheet, which is a representative material having a lighter weight, an excellent impact resistance, and higher flexibility, compared with the glass plate. However, it is necessary to complement deficient physical properties of a plastic film commercially produced these days, compared with the glass plate. Particularly, it is most urgently necessary to improve water resistance and gas barrier properties among the physical properties of the plastic film, compared with the characteristics of the glass plate, and a barrier film showing excellence both in gas barrier properties and light transmittance is required.

PRIOR ART DOCUMENT

1. Japanese Laid-Open Patent Application No. 2007-090803

SUMMARY OF THE INVENTION

The present invention is directed to providing a barrier film applied to an organic or inorganic phosphor device, a display device, or a photovoltaic device to effectively block environmental chemical materials such as water or oxygen, protect an electronic device therein, and maintain excellent optical characteristics, and a method of manufacturing the same.

In one aspect, the present invention provides a barrier film. In one example, the barrier film of the present invention may be applied to an organic or inorganic phosphor device, a display device, or a photovoltaic device. The exemplary barrier film 10, as shown in FIG. 1, may sequentially include a base layer 14, a first dielectric layer 13, an inorganic layer 12, and a second dielectric layer 11, and satisfy General Formula 1. Here, the inorganic layer may have a refractive index of 1.65 or more. In addition, a thickness of the first dielectric layer may be less than 100 nm, and a thickness of the second dielectric layer may be equal to or larger than that of the first dielectric layer. That is, the thickness of the second dielectric layer may be equal to or larger than that of the first dielectric layer. Meanwhile, the inorganic layer may have a refractive index of at least 1.65 or more, for example, 1.7 or more, 1.75 or more, 1.8 or more, 1.85 or more, 1.9 or more, 1.95 or more, 1.96 or more, 1.97 or more, 1.98 or more, 1.99 or more, or 2.0 or more. The upper limit of the refractive index of the inorganic layer may be, but is not particularly limited to, for example, 3.0 or less, 2.5 or less, 2.4 or less, 2.3 or less, or 2.2 or less. The present invention may provide a barrier film having gas barrier properties and excellent optical characteristics by controlling the thicknesses and refractive indices of the first dielectric layer and the second dielectric layer in addition to the inorganic layer having a relatively high refractive index. n ₂ ≤n ₁ <n _(i)  [General Formula 1]

In General Formula 1, n₁ represents the refractive index of the first dielectric layer, n₂ represents the refractive index of the second dielectric layer, and n_(i) represents the refractive index of the inorganic layer.

Optical characteristics of the film having a structure in which several layers are laminated are changed by the refractive indices and thicknesses of the components layer. Particularly, since the reflection and refraction of light occur at an interface between two layers having different refractive indices, the laminating materials, which give rise to the difference in refractive index among the laminated layers, and the lamination sequence have profound effects on the optical characteristics of the multilayer film. The first dielectric layer, the inorganic layer, and the second dielectric layer may be formed of materials known to those of ordinary skill in the art without limitation as long as the materials satisfy the relationship of the refractive indices, and as the relationship of the refractive indices and the thickness relationship are satisfied, the barrier film having excellent optical characteristics may be manufactured.

The term “refractive index” used herein may be, unless particularly defined, a refractive index in the range of a wavelength from 300 to 1000 nm. In one example, the “refractive index” used herein may refer to a refractive index in a wavelength of 550 or 633 nm.

In addition, the barrier film of the present invention having excellent optical characteristics may be manufactured by satisfying the thickness relationship according to General Formula 4. 0.01≤d ₁ /d ₂≤1  [General Formula 4]

In General Formula 4, d₁ is the thickness of the first dielectric layer, and d₂ is the thickness of the second dielectric layer.

As described above, a ratio of the thickness of the first dielectric layer d₁ to the thickness of the second dielectric layer d₂ may be 0.01 to 1, or 0.01 or more and less than 1, for example, 0.02 to 1.0, 0.05 to 1.0, 0.1 to 1.0, 0.1 to 0.9, 0.1 to 0.8, or 0.1 to 0.7. As described above, as the ratio of the thickness between the first dielectric layer and the second dielectric layer is limited to a specific range, a film having excellent gas barrier properties and light transmittance may be manufactured.

As described above, the thickness of the first dielectric layer d₁ may be less than 100 nm, for example, 5 to 98 nm. In addition, the thickness of the first dielectric layer may be 10 to 95 nm, 10 to 90 nm, 10 to 85 nm, 10 to 80 nm, or 10 to 75 nm. That is, the relationship of the thickness between the first dielectric layer and the second dielectric layer, which satisfies General Formula 4 of the present invention, may be established when, for example, the thickness of the first dielectric layer is less than 100 nm. In addition, in one example, the thickness of the second dielectric layer d₂ may be 10 nm to 1 μm, 10 to 900 nm, 20 to 800 nm, 30 to 700 nm, 35 to 600 nm, 40 to 500 nm, or 45 to 400 nm. As the thickness relationship is satisfied, the first dielectric layer and the second dielectric layer of the present invention may realize excellent gas barrier properties and light transmittance with the following zinc oxide-based inorganic layer having a higher refractive index than a silicon oxide-based inorganic layer.

In addition, in an exemplary embodiment of the present invention, the refractive index of the first dielectric layer n₁ and the refractive index of the second dielectric layer n₂ may satisfy General Formula 2. 0.5≤(n ₂−1)/(n ₁−1)≤1  [General Formula 2]

As shown in General Formula 2, the ratio (n₂−1)/(n_(i)−1) of the refractive index of the second dielectric layer n₂ to the refractive index of the first dielectric layer n₁ may be 0.5 to 1, preferably, 0.55 to 1, 0.6 to 1, 0.65 to 1, or 0.7 to 1.

In addition, in an exemplary embodiment of the present invention, the refractive index of the first dielectric layer n₁ and the refractive index of the inorganic layer n_(i) may satisfy General Formula 3. 0.3≤(n ₁−1)/(n _(i)−1)≤0.95  [General Formula 3]

As shown in General Formula 3, the ratio (n₁−1)/(n_(i)−1) of the refractive index of the first dielectric layer n₁ to the refractive index of the inorganic layer n_(i) may be 0.3 to 0.95, preferably 0.35 to 0.85, 0.4 to 0.8, 0.4 to 0.75, 0.4 to 0.7, or 0.45 to 0.7.

According to the present invention, a film having excellent light transmittance may be manufactured by limiting the ratio of the refractive indices between the first dielectric layer and the second dielectric layer and/or the ratio of the refractive indices between the inorganic layer and the second dielectric layer in a specific range.

In an exemplary embodiment of the present invention, the refractive index of the base layer may be, but is not particularly limited to, 1.45 to 1.75, 1.45 to 1.7, or 1.5 to 1.65. As long as satisfying General Formula 1, the refractive index of the first dielectric layer n₁ or the refractive index of the second dielectric layer n₂ may be, but is not particularly limited to, 1.35 to 1.9, 1.4 to 1.9, 1.45 to 1.9, or 1.45 to 1.8.

In addition, when the refractive index of the base layer is n_(s), the refractive index of the base layer may be lower than the refractive index of the inorganic layer n_(i). In one example, the refractive index of the base layer n_(s) and the refractive index of the inorganic layer n_(i) may satisfy General Formula 5. n _(s) <n _(i)  [General Formula 5]

In the present invention, the refractive index of the base layer n_(s) and the refractive index of the first dielectric layer n₁ may also satisfy General Formula 6. 0.5≤n _(s) /n ₁≤1.5  [General Formula 6]

That is, the material for the base layer of the present invention is not particularly limited, but may satisfy General Formula 5 or 6. For example, the ratio (n_(s)/n₁) of the refractive index of the base layer n_(s) to the refractive index of the first dielectric layer n₁ may be 0.5 to 1.5, and specifically, 0.6 to 1.4 or 0.7 to 1.3.

The relationship between the thickness of the first dielectric layer and that of the second dielectric layer of the barrier film may be suitably controlled according to material characteristics and relationship of the refractive indices of the layers, and characteristics of the inorganic layer of the barrier film, and satisfy General Formula 4. For example, as the thickness relationship is satisfied, excellent gas barrier properties and light transmittance may be realized with a zinc oxide-based inorganic layer that will be described below.

The barrier film may also have excellent light transmittance in the visible region. In one example, the present invention may exhibit light transmittance of 88% or more in the wavelength range of 380 to 780 nm. In the present invention, the barrier film sequentially including the base layer, the first dielectric layer, the inorganic layer, and the second dielectric layer may maintain excellent transparency. For example, the barrier film formed by satisfying the specific relationship of the refractive indices among the layers or the relationship of the thickness ratio may have light transmittance of 88% or more, 89% or more, or 90% or more in the range of a wavelength from 380 to 780 nm.

In addition, the barrier film may exhibit a lower yellowness index and excellent light transmittance. In one example, when the specific relationship of the refractive indices among the layers or the relationship of the thickness ratio is satisfied, the barrier film having a lower yellowness index may be provided. For example, the yellowness index according to ASTM E313 may be −2.0 to 2.0, −1.8 to 1.8, −1.5 to 1.9, or −1.3 to 1.8.

In addition, the barrier film may have a b* value of the CIE coordinate system in a range of −1.0 to 1.5 or −0.5 to 1.3. The CIE coordinate system is a color level defined in the Commission Internationale de l'Eclairage (CIE), and is also referred to as the CIE colorimetric system or the CIE color space. The coordinate system is a uniform color space coordinate, and a coordinate system today standardized in the world because it has very small difference from the color recognition of human eyes. The CIE coordinate system is defined by L* denoting brightness and a* and b* denoting chromaticity, and the a* and b* represent directions of the color. Specifically, when the a* value is a positive number, it represents the red direction, when the a* value is a negative number, it represents the green direction, when the b* value is a positive number, it represents the yellow direction, and when the b* value is a negative number, it represents the blue direction. The b* value of a barrier film may be determined by a known method.

In an exemplary embodiment of the present invention, the first dielectric layer, the inorganic layer, and the second dielectric layer may use a variety of materials which can be known by those of ordinary skill in the art without limitation as long as the relationship of the refractive indices represented by General Formula 1 and the thickness relationship are satisfied.

In one example, the base layer may include at least one selected from the group consisting of a polyester-based resin such as polyethyleneterephthalate, polycarbonate, polyethylenenaphthalate, or polyarylate, a polyether-based resin such as polyethersulfone, a polyolefin-based resin such as a cyclo-olefin polymer, a polyethylene resin, or a polypropylene resin, a cellulose-based resin such as diacetylcellullose, triacetylcellullose, or acetylcellullosebutylate, a polyimide-based resin, and an epoxy-based resin. In the present invention, preferably the base layer may include polycarbonate or a cyclo-olefin polymer. In one example, a thickness of the base layer may be, but is not particularly limited to, 2 to 200 μm, preferably, 5 to 190 μm, 10 to 180 μm, 20 to 180 μm, or 20 to 150 μm. In addition, the base layer may include a separate coated layer laminated on an opposite surface of the above-described multilayer laminate. The coated layer may be laminated to a thickness of 0.01 to 10 μm to improve optical characteristics, complement mechanical properties, or give functionality to make a future process easy.

The material for the inorganic layer is not limited as long as the above-described range of the refractive index is satisfied, and may be formed of, for example, an oxide or nitride of at least one metal selected from the group consisting of Al, Zr, Ti, Hf, Ta, In, Sn, Zn, and Si. The thickness of the inorganic layer may be 5 to 100 nm, 10 to 90 nm, or 10 to 80 nm. In one example, the inorganic layer of the present invention may be formed of a zinc oxide-based material. The zinc oxide-based material may be a zinc oxide-based material not containing any dopant, or a zinc oxide-based material containing dopants. The dopant which can be doped to the zinc oxide may be, but not limited to, at least one element selected from the group consisting of Ga, Si, Ge, Al, Sn, Ge, B, In, Tl, Sc, V, Cr, Mn, Fe, Co, and Ni, or an oxide thereof. The dopant may be doped to zinc oxide (ZnO) in the type of a cation, which substitutes a Zn moiety and increases the concentration of electrons or holes of the zinc oxide-based inorganic layer. However, not to degrade electron mobility, the concentration of the dopant may be 0.1 to 20 wt %. Alternatively, when mechanical properties and optical characteristics are adjusted using a dopant, the concentration of the dopant may be increased at 15 to 85 at %. In an exemplary embodiment of the present invention, the inorganic layer may be formed of, for example, zinc tin oxide as long as it satisfies the refractive index without particular limitation. As the zinc tin oxide is applied as the inorganic layer to the barrier film satisfying the above-described relation of the refractive indices and the thickness relationship, the barrier film may exhibit excellent gas barrier properties and optical characteristics.

In an exemplary embodiment of the present invention, the first dielectric layer or the second dielectric layer may be an organic or organic-inorganic composite layer. In one example, the first dielectric layer or the second dielectric layer may include at least one selected from the group consisting of an acrylic resin, a urethane-based resin, a melamine resin, an alkyde resin, an epoxy-based resin, a siloxane-based polymer, and an organic silane compound represented by Formula 1.

In Formula 1, X may be hydrogen, a halogen, an alkoxy group, an acyloxy group, an alkylcarbonyl group, an alkoxycarbonyl group, or —N(R₂)₂, in which R₂ is hydrogen or an alkyl group, R₁ is an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an arylalkyl group, an alkylaryl group, an arylalkenyl group, an alkenylaryl group, an arylalkynyl group, an alkynylaryl group, a halogen, an amino group, an amide group, an aldehyde group, an alkylcarbonyl group, a carboxyl group, a mercapto group, a cyano group, a hydroxyl group, an alkoxy group, an alkoxycarbonyl group, a sulfonyl group, a phosphoryl group, an acryloyloxy group, a methacryloyloxy group, or an epoxy group, Q is a single bond, an oxygen atom, or —N(R₂)—, in which R₂ is a hydrogen atom or an alkyl group, and m is a number of 1 to 3.

The organic silane may be at least one selected from the group consisting of the compound represented by Formula 1, and when a type of organic silane compound is used, crosslinking can occur.

An example of the organic silane may be selected from the group consisting of methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, phenyldimethoxysilane, phenyldiethoxysilane, methyldimethoxysilane, methyldiethoxysilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, triphenylmethoxysilane, triphenylethoxysilane, phenyldimethylmethoxysilane, phenyldimethylethoxysilane, diphenylmethylmethoxysilane, diphenylmethylethoxysilane, dimethylmethoxysilane, dimethylethoxysilane, diphenylmethoxysilane, diphenylethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, p-aminophenylsilane, allyltrimethoxysilane, n-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-glycidoxypropyldiisopropylethoxysilane, (3-glycidoxypropyl)methyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, n-phenylaminopropyltrimethoxysilane, vinylmethyldiethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, and a mixture thereof.

In one example, the first dielectric layer or the second dielectric layer may further include at least one selected from the group consisting of pentaerythritol triacrylate, hydroxyethylacrylate, hydroxypropylacrylate, polyethyleneglycol monoacrylate, ethyleneglycol monoacrylate, hydroxybutylacrylate, glycidoxymethacrylate, propyleneglycol monoacrylate, trimethoxysilylethyl epoxycyclohexane, acrylic acid, and methacrylic acid.

In one example, the epoxy-based resin may be at least one selected from the group consisting of an alicyclic epoxy resin and an aromatic epoxy resin.

The alicyclic epoxy resin may be, for example, at least one selected from the group consisting of an alicyclic glycidyl ether-type epoxy resin and an alicyclic glycidyl ester-type epoxy resin. In addition, as an example, Celloxide 2021P (Daicel), that is, 3,4-epoxycyclohexyl-methyl-3,4-epoxycyclohexane carboxylate, and derivatives thereof may be used, which may be stable at a high temperature, colorless and clear, and have excellent toughness, adhesion and adhesive strength for a laminate. Particularly, when the alicyclic epoxy resin is used for coating, excellent surface hardness is exhibited.

The aromatic epoxy resin may be at least one aromatic epoxy resin selected from the group consisting of a bisphenol A-type epoxy resin, a bromo bisphenol A-type epoxy resin, a bisphenol F-type epoxy resin, a bisphenol AD-type epoxy resin, a fluorene-containing epoxy resin, and a triglycidyl isocyanurate.

An inorganic material for forming the first dielectric layer or the second dielectric layer may be a coating composition formed by a sol-gel reaction, for example, at least one selected from the group consisting of SiO_(x) (wherein x is an integer of 1 to 4), SiO_(x)N_(y) (wherein x and y are each an integer of 1 to 3), Al₂O₃, TiO₂, ZrO, and ITO.

In addition, the first dielectric layer or the second dielectric layer may further include at least one selected from the group consisting of a metal alkoxide compound represented by Formula 2.

In Formula 2, M is any one metal selected from the group consisting of aluminum, zirconium and titanium, R₃ is a halogen, an alkyl group, an alkoxy group, an acyloxy group or a hydroxyl group, and z is 3 or 4.

In an exemplary embodiment of the present invention, the first dielectric layer or the second dielectric layer may further include a filler of nanoparticles to adjust the refractive index. The filler may be, but is not limited to, a metal oxide or a metal nitride. In one example, the filler may include at least one selected from the group consisting of CaO, CaF₂, MgO, ZrO₂, TiO₂, SiO₂, In₂O₃, SnO₂, CeO₂, BaO, Ga₂O₃, ZnO, Sb₂O₃, NiO, and Al₂O₃. In addition, when the filler is used in coating for a dielectric layer, a surface of the filler may be treated as needed to improve an adhesive strength. For example, the surface of the filler may be treated with epoxy silane, acryl silane, or vinyl silane. The filler may have a diameter of 0.1 to 150 nm, 0.1 to 100 nm, 1 to 90 nm, 1 to 70 nm, or 1 to 50 nm. As the size of the filler is controlled in the above range, transparency and a desired refractive index of the film of the present invention may be satisfied.

The first dielectric layer or the second dielectric layer may be cured by thermal curing, photocuring, or a combination thereof, and may further include a thermal acid generator or a photo acid generator as needed.

When the curing is performed with heat, thermal resistance of the base layer should be considered, and an amorphous base layer may be cured at a glass transition temperature or less, and if having crystallinity, the curing may be used at a higher temperature than the glass transition temperature. For example, a cyclo-olefin copolymer (COP) may be cured at 120° C. or less, polycarbonate (PC) may be cured at 130° C. or less, poly(ethylene terephthalate) (PET) may be cured at 130° C. or less, and polyethylenenaphthalate (PEN) may be cured at 150° C. or less.

The present invention also relates to a method of manufacturing the above-described barrier film. The exemplary manufacturing method may include sequentially laminating a first dielectric layer, an inorganic layer having a refractive index of 1.65 or more, and a second dielectric layer on a base layer. In addition, the first dielectric layer, the inorganic layer, and the second dielectric layer may satisfy General Formula 1, the thickness of the first dielectric layer may be less than 100 nm, the thickness of the second dielectric layer may be equal to or larger than the thickness of the first dielectric layer. n ₂ ≤n ₁ <n _(i)  [General Formula 1]

In General Formula 1, n₁ is a refractive index of the first dielectric layer, n₂ is a refractive index of the second dielectric layer, and n_(i) is a refractive index of the inorganic layer.

To sequentially form the first dielectric layer, the inorganic layer, and the second dielectric layer on the base layer, vacuum evaporation, sputtering, atomic layer deposition, ion plating, or coating may be used, but the present invention is not limited thereto, and thus a common method known to the art may be used.

EFFECT

A barrier film of the present invention can be applied to an organic or inorganic phosphor device, a display device, or a photovoltaic device to effectively block chemical materials such as water or oxygen, protect an electronic device therein, and maintain excellent optical characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an exemplary barrier film according to the present invention.

DESCRIPTIONS OF REFERENCE NUMERALS

-   -   10: barrier film     -   11: second dielectric layer     -   12: inorganic layer     -   13: first dielectric layer     -   14: base layer

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the present invention will be described in further detail with reference to examples according to the present invention and comparative examples not according to the present invention. However, the scope of the present invention is not limited to the following examples.

Example 1

A first dielectric layer having a refractive index of 1.65 was formed to have a thickness of 40 nm on a polycarbonate (PC) film (thickness: 100 μm, refractive index: 1.61) using a coating solution (TYT65, Toyo Ink Co., Ltd.) prepared by including metal oxide nanoparticles (titanium dioxide) in an acryl resin. Specifically, the coated layer was formed by coating the PC film with the coating solution using a meyer bar, drying the coated film at 100° C. for approximately 2 minutes, and irradiating the dried film with UV rays for coating at an intensity of 0.5 J/cm². Zinc tin oxide having a refractive index of 2.0 was deposited on the film coated as described above as an inorganic layer to a thickness of approximately 20 nm by sputtering in a 3 mTorr argon atmosphere. A second dielectric layer having a refractive index of 1.48 was formed on the deposited layer to a thickness of 91 nm using a coating solution prepared of pentaerythritol triacrylate and methylethoxy silane in a weight ratio of 40:60, and thus a barrier film was manufactured. Specifically, a half of the total weight of the pentaerythritol triacrylate used in the coating solution was a reaction product with isocyanato triethoxysilane. The coating solution was prepared by hydrating a mixture of the pentaerythritol triacrylate and methoxysilane using 2 equivalent of water based on silanol and 1.5 parts by weight of 0.1 N hydrochloric acid based on the solid content at room temperature for 30 hours. The second dielectric layer was formed by coating the PC film with the coating solution using a meyer bar, drying the coated film at room temperature for 3 minutes, and drying the resulting product at 100° C. for 1 minute.

Comparative Example 1

A barrier film was manufactured by the same method as described in Example 1, except that a first dielectric layer was formed to have a thickness of 91 nm, and a second dielectric layer was formed to have a thickness of 40 nm.

Comparative Example 2

A barrier film was manufactured by the same method as described in Example 1, except that a dielectric layer (thickness: 40 nm) having a refractive index of 1.48 was formed as a first dielectric layer using a coating solution prepared of pentaerythritol triacrylate and methylethoxy silane in a weight ratio of 40:60, and a dielectric layer (thickness: 91 nm) having a refractive index of 1.65 was formed as a second dielectric layer using a coating solution (TYT65, Toyo Ink Co., Ltd.) including metal oxide nanoparticles in an acryl resin.

Example 2

A barrier film was manufactured by the same method as described in Example 1, except that a first dielectric layer was formed to have a thickness of 20 nm and a second dielectric layer was formed to have a thickness of 100 nm.

Comparative Example 3

A barrier film was manufactured by the same method as described in Example 2, except that a second dielectric layer was not used.

Example 3

A barrier film was manufactured by the same method as described in Example 1, except that a PET film (thickness: 50 μm, refractive index: 1.64) was used as a base layer, a first dielectric layer was formed to have a thickness of 40 nm, and a second dielectric layer was formed to have a thickness of 100 nm.

Example 4

A barrier film was manufactured by the same method as described in Example 1, except that a cyclo-olefin copolymer (COP) film (thickness: 50 μm, refractive index: 1.53) was used as a base layer, a first dielectric layer was formed to have a thickness of 35 nm, and a second dielectric layer was formed to have a thickness of 960 nm.

Comparative Example 4

A first dielectric layer having a refractive index of 1.48 was formed on a PC film (thickness: 100 μm, refractive index: 1.61) to a thickness of 0.1 μm using a coating solution prepared of pentaerythritol triacrylate and methylethoxy silane in a weight ratio of 40:60. A zinc tin oxide layer having a refractive index of 2.0 was deposited on the coated film as an inorganic layer to a thickness of approximately 20 nm by sputtering in a 3 mTorr argon atmosphere. A second dielectric layer was formed on the deposited layer to a thickness of 0.26 μm using the coating solution, and thus a barrier film was manufactured.

Example 5

A barrier layer was formed by the same method as described in Example 4, except that a first dielectric layer was formed to have a thickness of 75 nm, and a second dielectric layer was formed to have a thickness of 75 nm.

1. Measurement of Refractive Index and Thickness

Refractive indices and thicknesses of the first dielectric layers, the second dielectric layers, and the inorganic layers according to Examples and Comparative Examples of the present invention were measured by the following methods.

Samples for measuring a refractive index were prepared by forming a dielectric layer or an inorganic layer on a Si substrate. The refractive index of the sample was obtained by analysis using an ellipsometer (M2000U, J.A. Woolam Co.).

The thicknesses of layers coated on a base layer were measured using a scanning electron microscope (S4800, Hitachi).

2. Measurement of Average Light Transmittance

Optical transmission spectrums of the barrier films manufactured according to Examples and Comparative Examples were evaluated using Shimadzu UV3600 (average light transmittance from 380 to 780 nm).

3. Measurement of Water Vapor Transmission Rate (WVTR)

WVTRs of the barrier films manufactured according to Examples and Comparative Examples were evaluated using Lyssy L80 at 30° C. and 100% R.H.

4. Measurement of Yellowness Index and CIE Value

Yellowness index (according to ASTM E313) and a* and b* values in the CIE color coordinates of the barrier films manufactured according to Examples and Comparative Examples were obtained from a light transmission spectrum using a utility provided by Shimadzu.

TABLE 1 Average light Yellow- WVTR transmittance ness (g/m² (%) a* b* index day) Example 1 90.7 −0.7 0.2 0.0 <0.03 Example 2 90.8 −1.0 1.3 1.8 <0.03 Example 3 91.7 −0.9 1.2 1.6 <0.03 Example 4 91.1 −0.7 −0.4 −1.3 <0.03 Example 5 90.2 −0.7 −0.4 −1.3 <0.03 Comparative 85.7 −0.1 1.3 2.5 <0.03 Example 1 Comparative 87.5 −0.2 −1.2 −2.5 <0.03 Example 2 Comparative 84.5 −0.1 2.9 5.6 <0.03 Example 3 Comparative 86.6 −0.6 −2.5 −5.5 <0.03 Example 4 

What is claimed is:
 1. A barrier film, sequentially comprising: a base layer, a first dielectric layer, an inorganic layer having a refractive index of 1.65 or more, and a second dielectric layer, wherein the first dielectric layer has a thickness of less than 100 nm, a thickness of the second dielectric layer is larger than that of the first dielectric layer, and wherein yellowness index according to ASTM E313 is −2.0 to 2.0, and wherein the barrier film satisfies General Formula 1 and General Formula 4: n ₂ ≤n ₁ ≤n _(i)   [General Formula 1] 0.01≤d ₁ /d ₂≤1   [General Formula 4] wherein n₁ represents a refractive index of the first dielectric layer, n₂ represents a refractive index of the second dielectric layer, n_(i) represents the refractive index of the inorganic layer, d₁ represents the thickness of the first dielectric layer, and d₂ represents the thickness of the second dielectric layer.
 2. The barrier film according to claim 1, wherein the thickness of the second dielectric layer d₂ is 10 nm to 1 μm.
 3. The barrier film according to claim 1, wherein the refractive index of the first dielectric layer n₁ and the refractive index of the second dielectric layer n₂ satisfy General Formula 2: 0.5≤(n ₂−1)/(n ₁−1)≤1   [General Formula 2].
 4. The barrier film according to claim 1, wherein the refractive index of the first dielectric layer n₁ and the refractive index of the inorganic layer n_(i) satisfy General Formula 3: 0.3≤(n ₁−1)/(n _(i)−1)≤0.95   [General Formula 3].
 5. The barrier film according to claim 1, wherein a refractive index of the base layer is 1.45 to 1.75.
 6. The barrier film according to claim 1, wherein the refractive index of the base layer n_(s) and the refractive index of the inorganic layer n_(i) satisfy General Formula 5: n _(s) <n _(i)   [General Formula 5].
 7. The barrier film according to claim 1, wherein a refractive index of the base layer n_(s) and a refractive index of the first dielectric layer n_(i) satisfy General Formula 6: 0.5≤n _(s) /n ₁≤1.5   [General Formula 6].
 8. The barrier film according to claim 1, wherein a refractive index of the first dielectric layer n₁ or a refractive index of the second dielectric layer n₂ is 1.35 to 1.9.
 9. The barrier film according to claim 1, wherein the inorganic layer comprises an oxide or nitride of at least one metal selected from the group consisting of Al, Zr, Ti, Hf, Ta, In, Sn, Zn and Si.
 10. The barrier film according to claim 1, wherein the inorganic layer is formed of zinc tin oxide.
 11. A method for preparing the barrier film according to claim 1, comprising: sequentially laminating on a base layer a first dielectric layer, an inorganic layer having a refractive index of 1.65 or more, and a second dielectric layer, which satisfy General Formula 1: n ₂ ≤n ₁ ≤n _(i)   [General Formula 1] wherein n₁ represents a refractive index of the first dielectric layer, n₂ represents a refractive index of the second dielectric layer, and n_(i) represents the refractive index of the inorganic layer; and wherein the first dielectric layer or the second dielectric layer comprises nanoparticles comprising on a surface thereof an epoxy silane, an acryl silane or a vinyl silane.
 12. The barrier film according to claim 1, wherein the first dielectric layer or the second dielectric layer is an organic or organic-inorganic composite layer.
 13. The barrier film according to claim 12, wherein the first dielectric layer or the second dielectric layer comprises at least one selected from the group consisting of an acrylic resin, a urethane-based resin, a melamine resin, an alkyd resin, an epoxy-based resin, a siloxane-based polymer, and an organic silane compound of Formula 1:

wherein X is hydrogen, a halogen, an alkoxy group, an acyloxy group, an alkylcarbonyl group, an alkoxycarbonyl group or —N(R₂)₂, in which R₂ is hydrogen or an alkyl group, R₁ is an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an arylalkyl group, an alkylaryl group, an arylalkenyl group, an alkenylaryl group, an arylalkynyl group, an alkynylaryl group, a halogen, an amino group, an amide group, an aldehyde group, an alkylcarbonyl group, a carboxyl group, a mercapto group, a cyano group, a hydroxyl group, an alkoxy group, an alkoxycarbonyl group, a sulfonyl group, a phosphoryl group, an acryloyloxy group, a methacryloyloxy group or an epoxy group, Q is a single bond, an oxygen atom or —N(R₂)—, in which R₂ is a hydrogen atom or an alkyl group, and m is a number of 1 to
 3. 14. The barrier film according to claim 12, wherein the first dielectric layer or the second dielectric layer comprises at least one selected from the group consisting of metal alkoxide compounds of Formula 2:

wherein M is one metal selected from the group consisting of aluminum, zirconium and titanium, R₃ is a halogen, an alkyl group, an alkoxy group, an acyloxy group or a hydroxyl group, and z is 3 or
 4. 15. The barrier film according to claim 1, wherein the first dielectric layer or the second dielectric layer further comprises nanoparticles.
 16. The barrier film according to claim 15, wherein the nanoparticles comprise a metal oxide or a metal nitride.
 17. The barrier film according to claim 15, wherein the nanoparticles comprise a material selected from the group consisting of CaO, CaF₂, MgO, ZrO₂, TiO₂, SiO₂, In₂O₃, SnO₂, CeO₂, BaO, Ga₂O₃, ZnO, Sb₂O₃, NiO, and Al₂O₃. 